Monitoring mites with a sticky board

A lot is written about how to monitor mite loads with a sticky board. A sticky board is just a piece of thin wood or corrugated plastic that is covered with a sticky substance—usually pan spray—and placed below a screened bottom board. A certain number of mites drop off and stick to the board. The board is usually left in place for one to three days and then the mites are counted and a “24-hour mite drop” is calculated.

Some beekeepers use this magic number to decide if and when to treat for mites, but ideas differ about what this number should be. As an example, the Brushy Mountain Bee Farm site suggests treating for mites if your 24-hour sticky board count is greater than 5-10 mites in the spring or 50-60 mites in the fall. Some sources use just one number. The Virginia Cooperative Extension site reads, “If more than 40 mites are recovered [in a 24-hour period], then the colony should be treated.”

How good are the numbers?

I have serious doubts about the validity of these numbers. The most obvious problem is that they do not take the hive population into account. A mite count of 40 in a single-deep, five-frame colony is very different than a count of 40 in a triple-deep, 24-frame colony. Mites per bee is the important number, not mites per bee hive.

Mite drop in the fall is greater than mite drop in the spring because, in the spring, most mites are under the capped cells where they are not going to fall off. Brushy Mountain recognized this in their estimate, but Virginia Cooperative Extension ignores it. Neither site discusses differences in mite count seen in various subspecies of honey bee, or differences in counts due to local climate or latitude.

The way I see it, the best we can hope for from a sticky board is to give us an idea of increase or decrease in mite loads. Or, if a beekeeper is diligent about estimating colony strength, he can assess mite drop as a function of colony strength and from there, decide when to treat.

Learning by doing

Like many issues in beekeeping, determining when to treat for mites is a skill learned by trial and error. It is nearly impossible to make “rules” that can be used successfully, although people keep trying. All beekeeping is local and all beekeepers are different. The main problem with teaching rules instead of concepts is that it gives new beekeepers false hope, and when they do everything the books, and their bees die anyway, they wonder if it’s worth it.

So what do I do? No sticky boards. Instead, when I need to do a mite count I use one of the more reliable methods such as a powdered sugar roll or an alcohol wash. The results obtained give you an estimate of mites per bee, and these tests are considered to be far more accurate than the sticky board.

For the past six years I’ve treated for mites once a year with one of the thymol-based products. I do this in August when brood is low and while there’s still time to raise a crop of winter bees that haven’t been exposed to mite-vectored viruses. I’ve had no problems with mites or mite-borne diseases until this year when I switched to HopGuard, but that’s an entirely separate subject. More on that later.

Rusty
HoneyBeeSuite

Comments

John
Reply

Speaking generally of mite control, do you advise screen or solid bottom boards for nucs? Going into my second year of bee keeping and thinking of keeping some spare queens in a mating nuc.
Love your site, sorry for your tree losses. Nature’s way of ‘pruning’ I guess.

Rusty
Reply

John,

I use screened bottom boards on everything, even nucs. I believe they are of marginal use for mite control, but they are a great source of ventilation. I never go without them.

Emily
Reply

At my apiary we often use cut-down estate agents boards smeared with vaseline. It is fun finding hundreds of mites on there after treating with oxalic acid in the winter. Another use for the board can be seeing how big the cluster is and where they’re feeding from the pollen and wax cappings dropped down onto the board.

Our National Bee Unit has a useful online varroa calculator at https://secure.fera.defra.gov.uk/beebase/public/BeeDiseases/varroaCalculator.cfm which takes into account the month of monitoring, brood rearing season and drone levels and advises whether you need to treat or not. It is UK oriented however as our colonies tend to be fairly small.

Rusty
Reply

Hi Emily,

Thanks for the link to the mite calculator. You bring up a good point about sticky boards–they can reveal a lot about the strength and location of your colony by just looking at the debris. Somewhere on this site I wrote a piece with photos of that very topic but, as keeps happening lately, I can’t find it. Anyway, I’m glad you reminded me. Also, I agree it is a good feeling to see mites stuck to the board–good riddance.

Robert
Reply

Is treating a captured swarm a good idea? There is no brood or honey. Seems like it would give them a clean start. Would it or would it damage them somehow?

Rusty
Reply

Just make sure they are settled in real well before you do it, otherwise they might abscond.

Robert
Reply

Can you do any of this with a regular bottom board? I plan on getting screened bottom boards, but at the moment only have solid. I do have some sticky-boards already. Would I be able to put that on-top of the solid board and would I then need something on top of it, like perhaps netting material, so the sticky-board doesn’t disrupt the bees?

Rusty
Reply

Robert,

Something would have to be on top so the bees wouldn’t stick to it, but the screen or netting would have to be large enough so mites could fall through. It sounds like a hassle to me.

RICH
Reply

Does anyone make a front-loading bottom board for the sticky board application?

Sarah Malone
Reply

I have cut holes in the center part of my old, solid wood bottom boards and covered with screen (recommended by Ross Conrad in Natural Beekeeping, Organic Approaches to Modern Apiculture, p. 125). Then I added a rail on either side of the bottom board (nails along the edge would also work), and cut a stiff piece of cardboard to slide in and out. Another beekeeper showed me how to use a screw to screw in a halved wine bottle cork to act as a handle to easily pull the makeshift board in and out. It fits in the front. I am going to make some boards that are only 1/2 size, to give the bees some protection from cold, but also continue with ventilation. Hope this helps.

Deb
Reply

Hi,
Have you done a post on the HopGuard switch? Of course now I’m curious.
Thanks!

Rusty
Reply

Deb,

Yes, there are several posts here on HopGuard, but none on HopGuard II, which I haven’t tried.

Dan
Reply

Rusty,

I’m real late to this party, but could you expand on this sentence from your post?

“I do this in August when brood is low and while there’s still time to raise a crop of winter bees that haven’t been exposed to the thymol.”

Is there a problem exposing the bees to the thymol? First year beekeeper and probably need to treat for mites.

Thanks

Rusty
Reply

Dan,

I’m really glad you wrote because that statement from a very old post needed to be changed. It’s not the thymol that’s the problem, it’s the virus. You want to raise winter bees that have not been exposed to bee viruses. This statement, from a later post, explains:

“Summer honey bees live four to six weeks, but winter bees can live six months or more. The winter survival of your colony is directly dependent on the health and vigor of those winter bees. If they are weakened by mites and viruses, your colony has little chance of survival.

But it’s your summer colony that has to raise the winter bees. To produce a healthy winter population, they must raise winter bees in an environment free of both Varroa mites and the diseases they carry. The winter bees will be raised in September or October, which means that in most of North America, your colony needs to be virtually mite-free by the first of September.”

Even since I wrote that, things have changed a bit. Some of the academic sites are now recommending that mite treatment be completed by August 15 instead of August 30. It depends on how far north you are, but I now go by the newer recommendation.

I’ve updated the post on sticky boards. Thanks for your help.

Deborah
Reply

Thanks. Do you no longer use OA?

Rusty
Reply

Deborah,

In order to reduce the chances of mites developing resistance to treatments, it is necessary to rotate your treatments. I rotate between thymol, formic, hops, and oxalic.

Dan
Reply

Hey Rusty, thanks for clarifying.

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